The invention relates to a process for producing color marks on a catheter guide wire of steel, to an apparatus for performing the process, and to a catheter guide wire of steel provided with color marks.
It has been known to use for the introduction of a catheter into a human body a metallic guide wire which imparts rigidity to the catheter and which, upon the introduction of the catheter is removed therefrom. Said leading-in technique is the so-called Seldinger technique, the respective guide wires being called Seldinger guide wires. To ensure that the guide wire is flexible enough to adapt itself to the contours of the blood vessels, it is made of one or more spirally wound leads. The guide wire also may include a core of longitudinally extending leads.
The known guide wires are provided with length marks allowing a determination of the length of the marking wire already introduced into the human body. The length marks are produced by printing, stamping or by laser beams, with the resultant disadvantage that the produced printing marks are prominent, or, in case of the laser beams, recessed. If printing ink is used, it is deposited between the helical turns sticking them together. Moreover, the printing ink may peel off if the guide wire is deformed. If the color marks consist of a pasted embossing sheet, the latter only adheres to the narrow circumferential surface of the spiral wire. Due to the small adhesive face, the embossing sheet may easily peel off. Further, marks are also applied by etching the spiral wire. Yet, in spite of repeated rinsings, residues of the etching agent may be left between the spiral turns or between the turns and the core.